In the back ground art of this technical field, the following are known as to an electric drill with a means for sensing a boring direction.
Publication 1: Japanese Patent Laid-open Publication No. Hei-7-214408 entitled as “Hand-type electric drill with level” (published on Aug. 15, 1995)
Publication 2: Japanese Patent Laid-open Publication No. Hei-10-225810 entitled as “Handy-type electric drill” (published on Aug. 15, 1998).